Clock synchronizing apparatus



Sept. 8, 1953 R. H. BARROWS CLOCK SYNCHRONIZING APPARATUS I Filed Nov.2:5, 1949 Patented Sept. 8, 1953 CLOCK SYNCHRONIZING APPARATUS RaymondH. Barrows, Johnson City, N. Y., assignor to International BusinessMachines Gorporation, New York, N. Y., a corporation of New YorkApplication November 23, 1949, SerialNo. 129,017

(01. SSE-.34)

1 Claim.

This invention relates to apparatus for synchronizing clocks, and inparticular, to apparatus wherein a master clock having an auxiliaryspring type motor and conventional escapement mechanism is controlledfrom a remote point by anelectrical impulse to come into synchronizationwith another master clock from which impulses originate.

Ordinarily clock systems comprised of master clocks and so-calledsecondary clocks, which are controlled by the master clock, aredependent for originating corrections of time upon a settin of themaster clock whereupon by devious means all of the secondary clocks arecaused to fall into synchronization, such synchronizing being carriedout at predetermined periods of time. One such system is explained andillustrated in U. Patent 1,878,931 to Larrabee. In some time systems themaster clock may be spring driven, in others an electric synchronousmotor may provide the drive, and in still others a combination of thetwo is used for initiating the driving of the master clock. An exampleof the lastdnentioned type of master clock driving mechanism is shown inU. S. Patent 2,424,119 to Best. A further application of a master clockin a time system such as has been previously referred to is shown in'aco-pending application, Serial No. 990 filed January '7, 1948, byJohnson and Geiger.

As explained in the co-pending application referred to above, it isobvious that in the case of an electrical power failure the synchronousmotor, which normally provides power for driving the master clockmechanism, is brought to rest whereupon a cooperating spring motor takesover the drive and operates until the synchronous motor is againrestored to its intended func-- tion. In some time systems two ormore'master clocks, sometimes referred to as slave master clocks, arecontrolled'by a single master clock of exceedingly high accuracy. Inthese systems the so-called slave master clocks each control a pluralityof secondary clocks and may themselves be corrected periodically from asingle supervisory master clock controllin all of the satellite timesystems. It is to such time-controlling devices that the presentinvention is particularly adapted.

The principal object of this invention is to provide a simple andefiective means for correcting clocks having spring driven motors bymeans of periodic electrical impulses.

Other objects of the invention will be pointed out in the followingdescription and claims and 2 illustrated in the accompanying drawings,which disclose, by way of examples, the principle of the invention andthe best mode, which has been contemplated, of applying that principle.

In Fig. l of the drawings a partial view of a clock mechanism is shownadapted to embody the present invention. The section of the clock shownin the drawing of Fig. 1 represents substantially the clock mechanismreferred to in the co-pending application discussed above, as indicatedby the corresponding reference characters. It is to be understood,however, that the present invention maybe embodied in any spring drivenclock having an escapement similar to that shown in the-drawings.

Fig. 2 of the drawings is a detail view illustrating the precise mannerof operation of the invention.

Now referring to Fig. 1 of the drawings a mounting plate 19 is arrangedto be fastened in an appropriate manner to a face plate 20 (see Figures1 and 2, application Serial No. 99-0, J anuary 7, 1948), so as toprovide a support for a yoke I3 of an electromagnet l2. Theelectromagnet I2 is positioned above a balance wheel 18 in suchamannerthat an iron slug H mount ed in the periphery of the balance wheel 18 ispositioned radially at approximately degrees from the pole tip l2 of themagnet when the balance wheel .18 is at rest. Normally when the springmotor is driving the mechanism the balance wheel 18 oscillates upon ashaft l0 regulatedbya spring 82 under the control of a regulatingarm I82having a bifurcated end I84 which traddles a regulating pin (not shown).It is to be understood that any conventional escapement mechanism may beemployed for driving the balance Wheel '58; however, for purposes ofclarificationthe marine escapement mechanism shown in the copendingapplication of reference may be considered most suitable. In thisconnection a small gear 86 mounted upon a seconds shaft 84, which isjournalled between the front plate 20 and a rear plate 22, meshes with alarge gear 62, which is driven by the spring motor, in such a way thatshaft 84 turns at a rate of 1 R. P. M. Acam I4 is also mounted on theshaft .84 to rotate with the gear v86. A pair of ontact straps H and I8.respectively, are mounted in an insulated plug which is supportedbetween the front andrear plates 20 and 22, respectively. Contacts; areprovided on the endsofthestraps l1 and 18 and abearing member l.5.isprovided on the strap I8 to cooperate with the cam 14 so that asshaft 84revolves the 3 contacts l6 will be made and broken for predeterminedperiods.

In operation the clock mechanism embodying the present invention isgiven sufficient potential energy by winding its main spring to drivethe gear 62 and operate the balance Wheel 18 thereby rotating the shaft8t at a predetermined rate of one revolution per minute. The regulatingarm I82 is then adjusted so that the balance wheel is oscillates at ahigher rate than is necessary to cause the clock mechanism to keepcorrect time; i. e., shaft 8 actually turns at a rate greater than 1 R.P. M., consequently the clock mechanism will gain time at a ratedepending upon the advancement of the regulating arm I82. At regularpredetermined intervals electrical impulses of predetermined durationare supplied from a suitable electrical source for energizing theelectromagnet i2 which through its pole tip 12a (Fig. 2) will attractthe slug H thereby stalling the balance wheel i8; consequently, asactual time progresses, the clock mechanism will remain inoperative forthe duration of each electrical impulse due to the balance wheel i8being held stationary, and a corresponding correction in time will bemade to compensate for the time normally gained.

One manner in which the above time correcting operation can be carriedout is by arranging the member I and the cam M so that contacts it Willbe closed for the first 210 degrees of each revolution of the shaft 84(corresponding in time to approximately the first 35 seconds of eachminute) and opened for the remaining 150 degrees of each revolution ofthe shaft 8 1 (correspending in time to approximately the last secondsof each minute). The clock movement is then regulated by means of thefork 182 to run at a fast rate so that it gains approximately onequarter of a second per minute, and a source for providing electricalimpulses is connected to the magnet E2, the contacts It being connectedin series therewith. Since contacts l6 are closed from the zero or 60seconds position to the seconds. position, an electrical impulse duringthis period will energize the magnet l2, which will therefore stop andretain the balance wheel 18 due to the magnetic attraction of the slugII and the pole tip [2a of magnet l2. During the period of rotation ofshaft 84 from the 35 seconds position to the zero or 60 seconds positionthe contacts it will be open and the magnet [2 can not be energized.

Let it be assumed that an electrical impulse of 2 seconds duration isdelivered to the magnet I2 via the series contacts l6 beginning the 58thsecond of each minute, and that such impulses are supplied regularly bya master clock such as disclosed in U. S. Patent 1,878,931. Also assumethat the mechanism shown in Fig. l of the drawings is incorporated intoa slave master clock having a spring motor drive, and that the clock ison time. Consequently when the 2 second impulse occurs, the shaft 84 ofthe slave clock will be at a position corresponding to the 58th secondand contacts it will be open so that the magnet i2 is not energized andno time correction is made. If the slave master clock is 1 second fast,for example, the shaft 84 will be at a position corresponding to the59th second when the 2 second impulse arrives (at the 58th second,actual correct time), and the contacts 16 will be open. However, thecontacts [6 will close when shaft 8% revolves to a positioncorresponding to the 60th second, and since the electrical impulse atthattime (one second later) has a remaining duration of 1 second, themagnet I2 will be energized to attract the slug ii in the balance wheel18, halting its oscillations for 1 second, the slave master clock willlose 1 second in time thereby being corrected to indicate the correcttime. Similarly a full correction of the slave master clock is made whenit is 2 seconds fast.

When the slave master clock is more than 2 seconds fast a correctionwill be made of the order of 2 seconds each minute until correct time isagain indicated by the slave master clock. With the arrangement of caml4 and member l5, described above, corrections up to 37 seconds fast inthe slave master clock can be compensated.

It is obvious that no correction can be effected electrically if theslave master clock is slow, except by regulating the arm I82 to causethe spring motor under control of the balance wheel 18 to drive shaft 84at a higher rate. For most practical purposes, however, a correction ofa fraction of a second per minute is sufficient in the slave masterclock so that the specific arrangement illustrated, by which the slavedevice gains a fraction of a second during the first part of each minuteand is corrected to lose what has been gained at the end of each minute,is quite adequate.

The principal advantage in apparatus of the type herein described is inits simplicity, its adaption to existing equipment Without majorredesign, and its smoothness of operation whereby the balance wheel of aspring clock is adjustedby magnetic force having no tendency to jam ordamage the delicate escapement mechanism therewith associated.

While there have been shown and described and pointed out thefundamental novel features of the invention as applied to a preferredembodiment, it will be understood that various omissions andsubstitutions and changes in the form and details of the deviceillustrated and in its operation may be made by those skilled in theart, without departing from the spirit of the invention. It is theintention, therefore, to be limited only as indicated by the scope ofthe following claim.

What is claimed is:

In a secondary clock for use in a clock system wherein a spring-drivensecondary clock is periodically brought into time agreement with amaster clock by an electrical impulse transmitted by the master clockduring the final portion of each of predetermined units of time, thecombination of a spring-driven marine escapement mechanism in saidsecondary clock including a balance Wheel constructed and arranged tooscillate about a normal rest position at a frequency greater than thatnecessary to measure accurate time as defined by the master clock andcomposed principally of a non-magnetic material, a magnetic slug insertmounted in the periphery of said balance Wheel, a time shaft rotatingunder control of said escapement mechanism at a rate in excess of onerevolution per said unit of time, electrical contacts, a cam on the saidshaft constructed to close said electrical contacts during an initialportion of said unit of time as measured by the secondary clock, anelectromagnet adjacent the periphery of said balance Wheel and solocated as to attract when energized the said slug and arrest theoscillation of said balance Wheel at an angular position of the balancewheel other than said normal rest position, a circuit in which saidcontacts and said electromagnet are connected for receiving theelectrical impulse from the master clock to energize said electromagnetwhen said cam closes said electrical contacts during said initialportion and when said initial portion concides with the transmission ofthe electrical impulse from the master clock.

RAYMOND H. BARROWS.

References Cited in the file Of this patent UNITED STATES PATENTS NumberNumber Name Date Von Orth July 10, 1894 Junghans May 16, 1939 HansenDec. 26, 1939 Mullan Apr. 30, 1940 Dicke July 8, 1941 FOREIGN PATENTSCountry Date France Apr. 9, 1934 Germany Feb, 23, 1938

